The present invention relates to a sickleless internal gear wheel pump for the generating of high pressure according to the generic term of patent claim 1.
A pump of this category is known from DE 41 04 397 Al.
Internal gear wheel pumps have in general an internally geared hollow wheel with which and externally geared pinion with lower number of teeth meshes, i.e. stands in engagement in driving. Each tooth tip of the hollow wheel has a profile groove. Into this groove a sealing element is inserted. In turning of the pinion this sealing element comes into sliding contact with its tooth tips. In the process there is briefly established a sealing-off, which blocks off the suction space against the pressure space. For the achieving of a certain contact pressure the radial outer ends of the sealing elements are acted upon with springs.
The sealing elements consist, as a rule, of plastic. There it was hitherto assumed that a certain elasticity is necessary in respect to the sealing-off.
In practical operation it has proved that, especially at relatively high operating pressures, there occur manifestations that were hitherto inexplicable. To these there belongs above all a decline of the efficiency of the pump. But also pressure pulsations have set in, which are extremely undesired.
Underlying the invention is the problem of constructing an internal gear wheel pump in such manner that neither a decline of the efficiency nor pressure pulsations manifest themselves.